Telephonic receiver



Oct. 12 1926.

A. H. MIDGLEY TELEPHONI C RECEIVER Filed August "25 1925 called loud speakers'than it'is in the or Patented Oct. 12, 1926.

UNITED ALBERT HENRY MIDGLEY, 0F UXBRIIDGE, ENGLAND.

TELEIIIQNIC eemwee Application filed bi s; 35,1325, Serial N 52.431, in Great Britain au st 21;, 1!?2 1.

This invention comprises improvements I A i H I w" )-P. Vi 1n and connected with telephonic receivers.

v these instruments 1t s very important, in" orderto obtain good reception, that'the' polepieces'of the magnets be very securely and solidly held in place. This"reqiiirementis' poss bly of greater importance in' the 'sodinary telephone ear piece receivers, but. ad vantage is tobe obtained in every case here the pole pieces are" secured in the manner referred to. It is of further importance, in coiisi'dering any m'ean's'to be adopted for achieving this end, that such means shall be capable of simple and'accurate reproduction inlarge numbers and of being easily and reliably assembled in manufacturing instru nients according to modern methods of prod wt' o ei The object of the present invention is to provide a magnet structure and means for securing the pole pieces therein vvhich Will satisfy all the requirements set outin the fore oin ara ra 3h.

b b According tov th s invention, the pole pieces are secured in asultable magnet structure by Wedges adapted for operating so that the wedging action does not iipset the accurate dispositipniiig of the pole piecesf Furthermore; the'po'le pieces maybe wedged against 'respectiveyoke pieces disposed betweenthe ends of paralle bar mag nets, these -yokepieees giving path of low magnetic resistance from the bars to the pole pieces and producing a solid magnet structure adapted for withstanding the powerful edging act-ion ezgertedin secfui'} ing the pole pieces.

' In. order to enable this invention to be readily understood; reference is made to the accompanyingdrawing illustrating two examples of practical embodiments of the invention, in Which clravving1:'

Figure 1 is a central vertical section of the portion of a loud speaker containing a magnet structure and pole pieces securedtherein in accordance With thisinvej n tion. I

Figure 2 is a horizontal section on the line II"II of Figure'lj Figure 3 is a perspective View of the magnet structure into which the pole pieces are fitte d and secured."

Figure 4 is a perspective View of two pole pieces removed from the structure seen in Figures 1 pole pieces. i Figure 6 is a sectional elevation illustratmg the Wedging of a moditied form ofp ole piece against a modified formof B oke piece;

Referring to Figures1and2,'t1ie loud speaker comprises af'base a on which mounted a diaphragm biii operative relation with the poles'o P0 6 Pieces 0', the diti phragm being shielded by acover' d formed with aspigot c for tie fittirigon of the stein of a horn or sound amplifier. The magnetstructure see also Figure [3, comprisespar allel bar magnets ivith stout yoke pieces a n bolted between them by bolts 0' 0, the endsof the bolt 0 being formed iv'ith 'centre recesses to act as'centre bearings for the centre 'points'of screws 9. It will be seen that this magnet structure mounted atoneend onthe centre bearings aforesaid, whereas" the other"'end is sjup; p'ei db p o i sat o fi s yo pi n" resting". upon a ho spring't supported by nuts'on screws 7). 0' are capable of being adjustedm earer to or further from the lia hra m 'bby ascrew the tui'niiigfof which either depresses the magnet structure about its pivot and against the resistancecf the permits the latter to elevate structure. This construction and arrangement of magnet is fully described and aimed in n t t esl ei nt the agne 1,582,770, dated April 27,1926.

The present improvements, as stated above, relate to the fixing of the pole pieces". It will be observed from Figures 2 and 3 that the inner ends of the yoke pieces 71 n is ,p vot'a i h s th Pol pie spring t" 01- 9o are of reduced Width so as to leave spaces 109 between them andthe bar magnets m, and it is to these reduced ends" that the pole pieces cl are secured.

The pole pieces 9 are assemblages of laminae, their upper portions ly formed for receiving megnet coils Q'in'the' usual manner. and theirlower portions be iiig formed With enlargements presenting on one side upper and lower inclined or Wedge surfaces 3, 4.

. l p laprop i t 9 The opposite or outer side of 110 the said "lower portions may be planar for fitting against planar surfaces of the ends of the yoke pieces a, n or they may also be formed with wedge surfaces as hereinafter described. Two rectangular pieces 5, 6 of brass or other suitable material, seen separately in Figure 5, are formed with bevelled edges corresponding with the wedge surfaces 3 and l, and with holes at the centre, the hole in the piece 5 being screw threaded.

The magnet structure being suitably supported in the manner above described, the pole pieces 0 are inserted into the gap between the yokes n, a with their planar faces against the end faces of the yoke pieces. The wedge piece 5, is inserted between the wedge surfaces 3 and the wedge piece 6 is inserted between the wedge surfaces i, a screw 7 being then passed through the piece 6 and screwed into the piece 5. Before tightening up the screw 7, the pole pieces are adjusted so that the pole tips are appropriately disposed in relation to the diaphragm b whereupon the screw 7 is tightened which effects a powerful drawing together of the wedge pieces and consequent pressing of the pole pieces against the yoke pieces 9%, n with such force as to secure the pole pieces strongly in their adjusted posi tion without any danger of shifting.

lVhen the pole pieces 0 are formed with wedge faces 3, l on one side only of their lower portions, the planar faces on the opposite side permit of the pole pieces being secured in desirably adjusted positions as explained. However, this may not be necessary, as for example in telephone ear pieces. In such cases, both sides of the lower portions of the pole pieces may be formed with wedge faces, as seen for example in Figure 6 in which the outer sides of the pole qaieces are formed with wedge faces 3, l corresponding with the wedge faces 3, 4. on the inner sides. The end faces of the yoke pieces are grooved giving corresponding wedge faces as seen in this figure. Upon tightening up the screw 7 in this construction, the pole pieces 0 will be rigidly secured by the wedging action on both sides, the position of pole pieces 0 being a fixed one, owing to the grooved end of the yoke pieces a, a.

As seen clearly in Figure 4-, the assemblages of laminae may be bound around the bottom and sides with a brass or other nonmagnetic strip 8. This strip may be enlarged and shouldered at 9 to provide a seating for the spools of the coils 2 when these latter are passed on to the pole pieces. The ends of the strip 8 Figure 4 may be bent over as at 10, to form abutments or clipping means for engaging the upper flange of the spool and retaining such spool upon the seating provided by the shoulders 9.

I claim 7 1. Telephone magnet comprising a robust magnet structure, individual pole pieces insertable into said structure, wedge devices engaging each of said pole pieces for securing same at the desired distance apart in said structure, and tightening means operativ'ely engaging said wedge devices.

2. Telephone comprising an adjustably mounted magnet structure, individual pole pieces, and mechanically operated wedge devices for securing the latter in spaced relation in said structure.

3. Telephone magnet comprising a parallel magnet structure, individual pole pieces disposed in the middle of said structure, and mechanically operated wedge devices securing the pole pieces in spaced relation in the structure.

a. Telephone magnet comprising parallel bar magnets, stout yoke pieces spacing said bar magnets, robust fixing means passing through said magnets and yoke pieces, pole pieces inserted between said yoke pieces, wedge devices inserted between said pole pieces, and mechanical tightening means operatively engaged with said wedge devices.

5. Telephone magnet comprising two separate pole pieces fixed in spaced relation in the magnet structure by opposed wedge devices operatively engaged by a mechanical adj ustment.

6. Telephone comprising a iiiagliet structure composed of bar magnets spaced apart at the ends by yoke pieces, pole pieces inserted between the inner faces of the yoke pieces, and opposed Wedge devices cooperating with wedge faces of said pole pieces for fixing the latter in said structure.

7 Telephone comprising a magnet structure composed of a. pair of parallel bar magnets, stout yoke pieces spacing said bars apart at respective ends, bolts bolting said bars and yoke pieces together, polar formations at the inner ends of said yoke pieces, pole pieces adapted to fit against respective polar formations, and wedge devices inserted between said pole pieces and operative to force the latter against the said polar formations substantially as set forth.

8. Telephone comprising a frame-like magnet structure, the side members being permanent magnetsand the end members being yokes, pole pieces abutting against respective yokes said pole pieces being spaced apart and forced against said yokes by opposed wedge devices engaging double wedge faces on said pole pieces.

ALBERT HENRY MIDGLEY. 

